Can Coal Propel Hypersonic Aeroplanes? Chinese scientists claim ‘big discovery’ in cutting Mach 5+ travel costs
In July this year, a small hypersonic prototype aircraft for civilian use, Nankiong No. China completed initial testing of the 1, paving the way for the development of a full-sized hypersonic aircraft. Now, Chinese scientists have made a breakthrough that could make hypersonic travel cheaper.
Chinese researchers recently claimed that the cost of commercial hypersonic flight could be significantly reduced by using an air-breathing engine that burns a mixture of ethylene and coal powder.
The researchers report their findings in a paper appearing in the September 15 issue of the peer-reviewed journal Acta Armamentarium. In a ground test, an experimental device using an inexpensive mixture produced shocks travelling at 2 km per second, or six times the speed of sound.
More Stories
“Coal powder’s excessive power density, protection and occasional fee make it a completely unique gain while used as an engine fuel,” stated the group led by way of Professor Weng Chunsheng of the National Key Laboratory of Transient Physics of Nanjing University of Science and Technology.
One of the most common byproducts of oil refineries is ethylene, and coal currently accounts for a large portion of China’s electricity generation. However, it is relevant to note that China had earlier faced an energy crisis due to shortage of coal, a situation that has now reversed.
Researchers test a component of the Nanqiang No. 1 hypersonic unmanned aerial vehicle at a laboratory in Fujian province. Image: Science and Technology Daily, Xiamen University,
The report, ambitious as it is, does not mention China’s decision to cut coal use to reduce emissions. Chinese President Xi Jinping promised last year to strictly control coal use and begin reducing it in 2026 to maximise the country’s greenhouse gas carbon dioxide (CO2) emissions before 2030.
That said, experts stress that the global economic downturn will not allow China to phase out coal as the president has vowed. In that context, the statements made by Chinese scientists have gained significance.
Beijing-based scientists previously reported in the EuroAsian Times that China is developing a hypersonic aircraft capable of carrying passengers anywhere in the world within an hour.
Another claims that the plane will cut the travel time from Shanghai to New York by up to 12 hours.
File photo: China’s hypersonic wind tunnel
For China’s hypersonic program to achieve smooth, long-range flight at Mach 7, Weng and his colleagues are developing detonation engine technology. It is a propulsion system that uses detonation waves to ignite a mixture of fuel and oxidizer.
Notably, in May of this year, Chinese researchers claimed that their air-breathing engine, fueled by inexpensive hydrocarbon fuel explosions, achieved stable performance during a simulated hypersonic test flight.
China to propel hypersonic aircraft on coal?
An experimental coal-fired engine generates thrust through a supersonic explosion by pushing microscopic coal particles, each about the size of a bacterium, into an oxygen-filled chamber. Then, it ignites them with electric sparks.
If the initial shock occurs quickly enough, the air compresses and further explosions occur, creating a strong and persistent forward thrust, the researchers said.
The team expects it to be at least 20% more efficient than contemporary jet engines, due to the engine’s incredibly rapid detonation ability to convert more chemical energy into kinetic energy.
It will be built to operate in a variety of situations, from airport takeoff to near-altitude hypersonic cruises in space.
According to Weng and his colleagues, the idea of using coal dust as an engine fuel was inspired by mine explosions, which instantly release enormous amounts of destructive energy.
However, igniting the explosion in a controlled manner is challenging. This is where ethylene comes in.
Because ethylene burns more easily than coal particles, it does not burn quickly enough to cause an explosion, the two combining to start a series of detonations.
Weng’s team tested the coal-ethylene fuel mixture under difficult conditions that can occur during flight, such as low electrical charge on the ground and excess or lack of oxygen. According to their published findings, the researchers discovered that the engine can move at any time and generate extremely rapid shock waves.
Hypersonic wind tunnel China
Defence and aerospace analyst Girish Linganna told the EuroAsian Times, “Generally, when looking for a propellant fuel, ethylene is looked at. This is due to its specific stimulation and concentration. There are better yet more expensive fuels that give the same thrust but are denser.
Therefore, the vehicle can travel longer distances or use smaller fuel reserves. The use of this fuel mix aims to reduce costs as well as replace limited resources with more ubiquitous fuel.
The idea of using coal to power hypersonic flight was put forward about ten years ago by researchers at the Russian Academy of Sciences, who demonstrated that shocks could be produced using a mixture of coal powder and hydrogen.
US research teams conducted additional research and developed some physical models to describe the complex system. Researchers in several countries, including China, are looking at alternative energy sources to fuel the future hypersonic travel business.
Along with China, the US is also developing hypersonic aircraft. Hypersonic aircraft have been on the US military’s priority list for some time. Lockheed Martin’s SR-71 Blackbird is the fastest fighter jet ever built.
Now, the US military is looking to build its successor.
